For Gasson, this morning's effort went a long way to making up for the disappointment of the opening day of the championship, when she narrowly missed qualification in the 200m butterfly, fading badly in the finals after a strong swim in the morning.
Gasson said she learnt a lot from her experience earlier in the week.
"I did not handle the pressure well at all, so I've seen a few people about it and tried to get my head right - I really needed to," she said.
"I just had to stay positive [for today's race]. I wasn't really thinking about the end time, I was just thinking about processes and how I was going to swim the race and if I did it how I knew I could, I knew I would do the time."
In all, three New Zealand records fell on day three of the championships, with Howick Pakuranga's Daniel Hunter setting a new best time in the 50m freestyle as he came agonisingly close to the Olympic qualifying time. Hunter's time of 22.31 was just 0.04 seconds outside the Fina 'A' standard swimmers need to better in order to make the grade for Rio.
In other near-misses, five-time World Championship medallist Lauren Boyle was just outside the Olympic qualifying time in the heats of the 400m freestyle. But Boyle, who qualified in the 800m freestyle on the opening night of the event, is expected to easily knock off the mark in this evening's finals.